Directed Self-Assembly Tutorial to be Featured at SEMI ASMC 2014

How Viable is DSA for Production Lithography in Commercial Semiconductor Fabrication?

Directed
Self-Assembly Tutorial to be Featured at SEMI ASMC 2014

by Eric
Eisenbraun and Paul Werbaneth­­

“As line widths drop to 7nm and beyond, EUV
may already be outdated. The future there may be directed self-assembly or some
other exotic technology that has been ignored for years in the struggle to get
EUV working.” (Ed Sperling, in SemiconductorEngineering,
27 February 2014.)

One of the most promising nanolithography techniques
now under consideration is Directed Self-Assembly (DSA). In DSA, resists that
contain block copolymers are deposited on top of guiding structures which are fabricated
on a silicon wafer’s surface using a conventional lithographic technique. Generally, the base layer is comprised of patterned resist,
and the DSA layer is a Block Co-Polymer (BCP). The self-directed nature of the BCP
assembly process results in very regular, controllable patterns with nanoscale resolution.

The DSA process typically involves a two-step
imaging/resist hardening cycle to form the base layer pattern, followed by
self-assembly of the BCP, which can be patterned using an oxygen-based reactive
ion etch (RIE) process. This results in well-defined nanoscale patterns.

[Source:
IBM / SPIE]

To date, 7nm features have been demonstrated
with this technique. A major advantage of DSA is that it is relatively low-cost
compared to other next-generation lithographic techniques. In addition, a
mature toolset and process technologies already exist to support DSA, and the
materials are well studied. As such, the prospects for manufacturability are
strong.

Increasingly, there are reports from around
the world about commercial DSA activity, such this press release from Arkema,
France’s leading chemical producer: “Europe launches PLACYD, a large consortium
to address Directed Self Assembly (DSA) Lithography.” According to Arkema, the PLACYD consortium of
industrial and academic collaborators will establish a dedicated material
manufacturing facility that allows the production of block copolymers meeting
the rigorous standards required for their use in industry as nanolithographic
templates for DSA. Partners in the
PLACYD consortium include Applied Materials, ASML, CEA-Leti, Intel, Mentor Graphics,
STMicroelectronics, and several European universities and academic research institutions.

PLACYD’s goals are to strengthen the commercial
partners’ position in their respective markets, and to secure and accelerate
the potential adoption of DSA lithography by the semiconductor industry as a
result of being poised to deliver important supply chain components, for example
a supply of characterized DSA materials and a proven DSA infrastructure.

At the recent (February 2014) SPIE Advanced Lithography
conference held in San Jose, Calif., directed self-assembly was represented
front and center, from the keynote talks (“Beyond Scaling: Opportunities and
Approaches,” by Akihisa Sekiguchi, Tokyo Electon, Ltd.) to the training courses
offered (“Directed Self Assembly and its Application to Nanoscale Fabrication”)
through to the conference tracks dedicated to Alternative Lithographic
Technologies. Many companies gave
DSA-related talks at SPIE, along with universities and research institutes from
across the globe.

How viable a candidate then is DSA for
production lithography in commercial semiconductor fabrication? As JSR Micro
says, “Creating order from disorder. On
the order of 10nm. Whatever the horizon brings – double patterning, EUV or DSA,
JSR Micro has the solution that is ready to go right now.”

That may be a bit optimistic about the state
of DSA in 2014, but to include DSA in the same breath as double patterning and
EUV means the semiconductor industry is serious about DSA’s prospects, and
likes having another horse enter the advanced photolithography race, whose
winner has yet to be crowned.

The upcoming SEMI Advanced
Semiconductor Manufacturing Conference 2014 (May 19-21) features
a tutorial on directed self-assembly taught by Michael A. Guillorn, Ph.D., research
staff member, manager Nanofabrication and Electron Beam Lithography, at the IBM
T. J. Watson Research Center. ASMC
tutorials have traditionally examined topics just on the horizon of
commercialization, and so it is timely that ASMC 2014 offers participants the
opportunity to learn more about the very important topic of DSA.

ASMC 2014 also features a panel discussion on
“25 Years of Semiconductor Manufacturing: Accomplishments, Current Challenges,
Future Directions — From the Internet to the Internet of Things,” with
panelists from SEMATECH, RIT, GLOBALFOUNDRIES, Qualcomm, and Applied Materials,
and there will be a second tutorial, on Silicon Photonics, taught by Dr.
Haisheng Rong, Intel.

ASMC 2014 is being held at the Saratoga
Hilton, located in the heart of beautiful, historic Saratoga Springs, New York,
just minutes from GLOBALFOUNDRIES Fab 8 in Malta, New York, and just 30 minutes
from the Albany International Airport, G450C, SEMATECH, and the College of
Nanoscale Science and Engineering.

Eric
Eisenbraun is an Associate Professor at the SUNY College of Nanoscale Science
and Engineering in Albany, New York.

Paul
Werbaneth is a Contributing Editor and member of the Technical Advisory Board
at 3D
InCites.